PROJECT SUMMARY/ABSTRACT Maternal obesity, gestational diabetes, and childhood obesity are part of a vicious cycle. Almost half of all reproductive-aged women in the United States are overweight or obese. Overweight and obese women are up to 6 times more likely to develop GDM than normal weight women. Children exposed to GDM in utero have an 8-fold greater type 2 diabetes risk and a 2-fold greater obesity risk, perpetuating the cycle. Increasing physical activity and sleep during pregnancy may help mitigate these risks. These behaviors are interrelated: improving one (e.g. getting more physical activity) could occur at the expense of another (e.g. getting enough sleep). The ideal daily pattern of physical activity and sleep to prevent pregnancy complications and subsequent childhood obesity risk factors is unknown. Despite the interrelated nature of these behaviors, prior research on physical activity, sedentary behavior, and sleep during pregnancy in overweight and obese pregnanct women has focused on individual associations of these behaviors with perinatal outcomes. How the interdependent relationships between physical activity, sedentary behavior, and sleep within a 24-hour movement framework affect perinatal outcomes remains unclear. The goal of this K99/R00 Pathway to Independence Award is to facilitate my transition to becoming an independent researcher with expertise in the 24-hour movement framework during pregnancy to ultimately develop interventions and guidelines for 24-hour movement during this critical period. During the Mentored (K99) Phase of this award, I will pursue training in the analysis of accelerometer-measured physical activity data, the physiology and measurement of sleep, and practical skills in research study conduct, including recruitment and retention, under the mentorship of Dr. Monique Hedderson (Primary Mentor), Dr. Kelley Pettee Gabriel (Co-Mentor and expert in accelerometer-measured physical activity within a 24-hour movement framework), and Dr. Rachel Manber (Co-Mentor and expert in sleep during pregnancy). My research during the Mentored Phase will 1) assess whether 24-hour movement profiles during early pregnancy are associated with late pregnancy maternal metabolic biomarkers, and 2) assess whether 24-hour movement profiles during early and late pregnancy are associated with delivering infants with childhood obesity risk factors using data from an existing study among overweight and obese pregnant women. In the Independent (R00) Phase of this award, I will examine longitudinal relationships of 24- hour movement profiles during pregnancy with glucose tolerance, birthweight, and neonatal adiposity by creating a cohort of overweight and obese pregnant women with daily, device-based measurement of physical activity, sedentary behavior, and sleep across pregnancy. These training and research activities will prepare me to successfully compete for R01 funding to support further investigation of 24-hour movement profiles and pregnancy outcomes in high-risk populations of pregnant women.